1. Field of Invention
This invention relates to a figure element revising method and, more particularly, to a figure element revising method for displaying and revising a group of figure elements including defined figure elements and figure elements defined using the defined figure elements.
2. Description of the Related Art
In an automatic programming system for creating NC data using an automatic programming language such as APT (automatic programming tools) or FAPT,
(a) a part program based on the automatic programming language is created by defining points, straight lines and circular arcs using simple symbols (this is referred to as "figure definition"), and then defining a tool path using the defined points, straight lines and circular arcs (referred to as "motion statement definition"), and
(b) the part program based on the automatic programming language is subsequently converted into NC data comprising NC data (EIA codes or ISO codes) in a format capable of being executed by an NC unit.
For example, in the creation of a figure definition statement based on the automatic programming language, figure definition is performed by defining a point P.sub.1 and circles C.sub.1, C.sub.2 as follows using a keyboard or tablet: EQU C.sub.1 =x.sub.1, y.sub.1, r.sub.1 ( 1) EQU C.sub.2 =x.sub.2, y.sub.2, r.sub.2 ( 2) EQU P.sub.1 =x.sub.3,y.sub.3 ( 3)
as shown in FIG. 8. A straight line S.sub.1 and a circle C.sub.3 are then defined as follows using the defined figure elements: EQU S.sub.1 =C.sub.1, C.sub.2, B, A (4) EQU C.sub.3 =P.sub.1, S.sub.1 (b 5)
In the foregoing,
equation (1) signifies a circle C.sub.1 of center (x.sub.1,y.sub.1) and radius r.sub.1 ;
equation (2) signifies a circle C.sub.2 of center (x.sub.2,y.sub.2) and radius r.sub.2 ;
equation (3) signifies a point whose coordinates are x.sub.3,y.sub.3);
equation (4) signifies a straight line (tangent) S.sub.1 that is tangent to the lower side of circle C.sub.1 and the upper side of circle C.sub.2 ; and
equation (5) signifies a circle C.sub.3 tangent to the straight line S.sub.1 and having he point P.sub.1 as its center. The alphabetic character A in (4) is a qualifier meaning "above", and the alphabetic character B is a qualifier meaning "below".
There are two methods of figure definition, as will be understood from the foregoing. A first definition method entails defining points, straight lines and circles using absolute numeric data. A point is defined as EQU P=x, y
using the coordinates (x,y) of the point [see FIG. 10(a)]; a straight line is defined as EQU S=x.sub.1, y.sub.1, x.sub.2, y.sub.2
using coordinate points (x.sub.1,y.sub.1), (x.sub.2,y.sub.2) of two points P.sub.1, P.sub.2 through which the straight line passes [see FIG. 10(b)]; and a circle is defined as EQU C=x, y, r
using the coordinates (x,y) of the center of the circle and the radius r of the circle [see FIG. 10(c)]. A figure definition statement based on the first definition method shall be referred to as a first definition statement.
The second definition method entails defining straight lines and circles using other points, straight lines and circles that have already been defined. For example, point P.sub.1 [see FIG. 10(d)] is defined as follows: EQU P.sub.1 =S,C, L
(the alphabetic character L is a qualifier meaning "left"); the straight lines S.sub.1, S.sub.2 [see FIG. 10(e)] are defined as follows: EQU S.sub.1 =C.sub.1, C.sub.2, A, A EQU S.sub.2 =C.sub.1, C.sub.2, B, B
(the alphabetic character A is a qualifier meaning "above", and the alphabetic character B is a qualifier meaning "below); and the circle C [see FIG. 10(f)] is defined as follows, by way of example: EQU C=S.sub.1 S.sub.2, S.sub.3, R, A, L
(the alphabetic character R is a qualifier meaning "right"). A figure definition statement based on the second definition method shall be referred to as a second definition statement. The foregoing method in which elements already defined are used to define other elements is only one example, there being many other methods of definition available.
When figure definition is performed, the arrangement is such that a figure element is defined by the first definition statement, and another figure element is defined by the second definition statement based on the figure element in accordance with the first definition statement.
There are cases where it is desired to modify the center (x.sub.2,y.sub.2) and radius r.sub.2 of the circle C.sub.2, which is an example of an already defined figure element (FIG. 8), to (x.sub.2 ',y.sub.2 ') and r.sub.2 ', respectively, to arrive at the circle indicated by the broken line in FIG. 9. When the definition statement of circle C.sub.2 is modified to EQU C.sub.2 =x.sub.2 ', y.sub.2 ',r.sub.2'
in such case, the straight line S.sub.1 defined as being tangent to the lower side of circle C.sub.1 and the upper side of circle C.sub.2 fails to exist and an error is generated. When the error occurs, automatic programming cannot resume until the error is removed. Consequently, in the prior art, it is necessary for the operator to manually call a figure definition statement revision screen, search for all error locations from the figure definition statement, perform redefinition, display the redefined figure element and verify the same. This is a troublesome operation.